1. Field of the Invention
This invention relates to a steering gear and control system for an automotive vehicle in which the prime mover for operating the steering gear comprises a linear electric motor.
2. Disclosure Information
Power assisted steering systems have been widely employed in automotive vehicles for a number of years. One common type of power assisted steering utilizes a hydraulic pump driven by the crankshaft of the vehicle engine, with the Pump being operatively connected with the steering gear so as to provide hydraulic boost to the driver's steering effort. Electrically driven power assist systems are also known. An example of such a system is disclosed in U.S. Pat. No. 4,785,901. Electrically driven power assist systems commonly utilize control algorithms having as their inputs steering driveshaft torque and vehicle velocity The torque sensor is adapted to respond to the steering load and the speed sensor is adapted to respond to the speed of the vehicle. Electrically powered steering systems also commonly utilize a control module for operating the electric prime mover. The electric prime movers commonly comprise geared rotary types of motors. Such gearing is costly and often quite complex. It is an advantage of the present invention that all such motor gearing and the rotary motor itself are replaced with a linear motor having but a single major moving component.
It is an object of the present invention to provide a linear motor equipped steering gear suitable for steering the rear roadwheels of a vehicle equipped with four-wheel steering.
It is a further object of the present invention to provide a four-wheel steering system using a linear motor either at only the rear position of the vehicle or at both the front and rear positions of the vehicle.
It is an advantage of the present invention that a four-wheel steering system using a linear motor steering gear at only the rear position of the vehicle, or at both the front and rear positions of the vehicle, will not require a driveshaft extending from the front steering gear to the rear steering gear.
Further objects, features and advantages of the present invention will become apparent to those skilled in the art in view of this specification.